Something like that is obviously needed. I don't know how my copy of the
code omitted the test for hauteur_soleil being > 0. There are a number of
sources from which I may have copied it, and I didn't keep links to all of
them, but I can't imagine why I would have deleted the test if my source
had included it. I will obviously add it to my working code.
On Friday, July 1, 2022 at 2:45:42 AM UTC-4 jterr...@gmail.com wrote:
> OK. What I don't understand is that my code had always a test
>
> if hauteur_soleil > 3: (according to Météo France)
>
> or more recently
>
> if hauteur_soleil > 0:
>
> in the function, and this test is not on your function.
>
> It should be :
>
> hauteur_soleil = asin(sin((pi / 180) * latitude) * sin((pi / 180) *
> declinaison) + cos(
> (pi / 180) * latitude) * cos((pi / 180) * declinaison) * cos((pi /
> 180) * angle_horaire)) * (180 / pi)
> If hauteur_soleil > 0:
>
> seuil = (0.73 + 0.06 * cos((pi / 180) * 360 * dayofyear / 365)) * 1080
> * pow(
> (sin(pi / 180) * hauteur_soleil), 1.25) * coeff
> else :
> seuil = 0
> return seuil
>
> Le 30 juin 2022 à 22:52, 'Peter Fletcher' via weewx-user <
> weewx...@googlegroups.com> a écrit :
>
> That was going to be my next step! In fact, iterating through a list of
> the dateTime values that produce the errors in the real code and passing
> each value to the function confirms that it is the specific dateTime values
> that are causing the function to misbehave. The returned results are all
> complex numbers with negative and numerically identical (for a given
> dateTime) real and imaginary components. It does seem to be a bug in the
> function. I assume that hauteur_soleil should always be >=0. It appears
> that, for my latitude and longitude and for the given specific values of
> dateTime, it becomes negative. The last step in the calculation then
> involves raising a negative number to a non-integral power, which is
> guaranteed to produce interesting results! The really odd thing is that
> math.pow is not returning a ValueError, which the docs say is what should
> happen under these circumstances, but apparently trying to return a
> (possibly) valid complex result.
> On Thursday, June 30, 2022 at 3:07:38 PM UTC-4 jterr...@gmail.com wrote:
>
>> The only clue I have is that the problem is not due to an « overloading »
>> of your raspberry pi, but seems to occur with specific dateTime values.
>> You can try to run your script only with a « bad » dateTime :
>>
>> "SELECT dateTime, Radiation from archive where dateTime = 1592614500 »
>>
>> Does the error occurs ? If yes, you can try to add debugging print
>> commands inside the sunshineThreshold function to try to understand.
>>
>>
>>
>> Le 30 juin 2022 à 19:51, 'Peter Fletcher' via weewx-user <
>> weewx...@googlegroups.com> a écrit :
>>
>> It did as it seems you predicted - passed 1592614800 and stopped at
>> 1632611100. You obviously have a clue as to what is going on. Please
>> explain!
>>
>> On Thursday, June 30, 2022 at 8:59:48 AM UTC-4 jterr...@gmail.com wrote:
>>
>>> If you exclude the first one,1592614500 , with a query like "SELECT
>>> dateTime, Radiation from archive where dateTime <> 1592614500", will the
>>> script stop at 1592614800 ( the next dateTime) or will it continue and stop
>>> at 1632611100 ?
>>>
>>> Le 30 juin 2022 à 14:34, 'Peter Fletcher' via weewx-user <
>>> weewx...@googlegroups.com> a écrit :
>>>
>>> 1592614500
>>> 1632611100
>>> 1632611400
>>> 1647688800
>>>
>>> I can't see a pattern or any common features.
>>>
>>> On Thursday, June 30, 2022 at 3:55:49 AM UTC-4 jterr...@gmail.com wrote:
>>>
>>>> No, I never had weewx crashes related to the sunshine calculations.
>>>>
>>>> What are the dateTime values that trigger the error ?
>>>>
>>>>
>>>>
>>>> Le mercredi 29 juin 2022 à 23:23:16 UTC+2, Peter Fletcher a écrit :
>>>>
>>>>> Have you had any odd weewx errors or crashes related to the sunshine
>>>>> calculations? I ask because I hadn't, but I decided to try to 'backfill'
>>>>> my
>>>>> database with sunshine times, based on the 5-minute radiation values, and
>>>>> I
>>>>> ran into a bizarre bug. I used the code shown below (on a copy of my live
>>>>> weewx database). As you will see, the threshold calculation code is
>>>>> essentially identical to yours, except that it has been converted to a
>>>>> regular function (no 'self' parameter) and my station's latitude and
>>>>> longitude are hard coded in it. When the code is run under Python 3.9.2
>>>>> on
>>>>> my Pi, it initially runs without problems, but crashes after 8,000+
>>>>> records
>>>>> have been processed with a ValueError on the MaxThreshold vs threshold
>>>>> comparison, reporting that it can't compare a complex with a float! If I
>>>>> intercept and log the errors, it turns out that, for a few specific
>>>>> values
>>>>> of dateTime, the function returns a complex number! Even more bizarrely,
>>>>> it
>>>>> only seems to do that in the context of the running code. If I manually
>>>>> run
>>>>> through all the operations from the function code at the Python command
>>>>> line, using the value of dateTime that produces the first crash, all the
>>>>> intermediate results and the final result are sane floats.
>>>>> There appears to be a second issue, possibly related to my reading and
>>>>> writing the database at relatively high frequency, which stalls the
>>>>> process
>>>>> after about 18,000 records have been processed, but removing the database
>>>>> writes allows it to run to completion without abolishing the consistent,
>>>>> albeit infrequent, ValueErrors.
>>>>>
>>>>> [backfill.py]
>>>>> import sqlite3
>>>>> from datetime import datetime
>>>>> import time
>>>>> from math import sin, cos, pi, asin
>>>>>
>>>>> def sunshineThreshold(mydatetime):
>>>>> coeff = 0.9 # change to calibrate with your sensor
>>>>> utcdate = datetime.utcfromtimestamp(mydatetime)
>>>>> dayofyear = int(time.strftime("%j", time.gmtime(mydatetime)))
>>>>> theta = 360 * dayofyear / 365
>>>>> equatemps = 0.0172 + 0.4281 * cos((pi / 180) * theta) - 7.3515 *
>>>>> sin(
>>>>> (pi / 180) * theta) - 3.3495 * cos(2 * (pi / 180) * theta) -
>>>>> 9.3619 * sin(
>>>>> 2 * (pi / 180) * theta)
>>>>>
>>>>> latitude = 43.0346213
>>>>> longitude = -78.689362
>>>>>
>>>>> corrtemps = longitude * 4
>>>>> declinaison = asin(0.006918 - 0.399912 * cos((pi / 180) * theta)
>>>>> + 0.070257 * sin(
>>>>> (pi / 180) * theta) - 0.006758 * cos(2 * (pi / 180) * theta)
>>>>> + 0.000908 * sin(
>>>>> 2 * (pi / 180) * theta)) * (180 / pi)
>>>>> minutesjour = utcdate.hour * 60 + utcdate.minute
>>>>> tempsolaire = (minutesjour + corrtemps + equatemps) / 60
>>>>> angle_horaire = (tempsolaire - 12) * 15
>>>>> hauteur_soleil = asin(sin((pi / 180) * latitude) * sin((pi / 180)
>>>>> * declinaison) + cos(
>>>>> (pi / 180) * latitude) * cos((pi / 180) * declinaison) *
>>>>> cos((pi / 180) * angle_horaire)) * (180 / pi)
>>>>> seuil = (0.73 + 0.06 * cos((pi / 180) * 360 * dayofyear / 365)) *
>>>>> 1080 * pow(
>>>>> (sin(pi / 180) * hauteur_soleil), 1.25) * coeff
>>>>> return seuil
>>>>>
>>>>>
>>>>> database = 'weewx.sdb'
>>>>>
>>>>> maxThreshold=0
>>>>> count=0
>>>>> conn=sqlite3.connect(database)
>>>>> cur=conn.execute("SELECT dateTime, Radiation from archive")
>>>>> for row in cur:
>>>>> count += 1
>>>>> if (row[1] is not None) and (row[1] > 20):
>>>>> threshold = sunshineThreshold(row[0])
>>>>> if threshold > maxThreshold:
>>>>> maxThreshold = threshold
>>>>> if row[1] > threshold:
>>>>> conn.execute("UPDATE archive set SunshineTime = 5 WHERE
>>>>> dateTime = " + str(row[0]))
>>>>> if count % 1000 == 0:
>>>>> print(count, 'Max Threshold', maxThreshold)
>>>>> conn.close
>>>>> [/backfill.py]
>>>>>
>>>>> On Friday, June 10, 2022 at 3:29:40 AM UTC-4 jterr...@gmail.com wrote:
>>>>>
>>>>>> On my side, I have looked at the CPU utilization on my raspberry Pi
>>>>>> 3B+. I have the mqtt service service installed, so at each loop all
>>>>>> data
>>>>>> of the packet are sent to the mqtt broker.
>>>>>>
>>>>>> With mqtt and when calculations of the sunshine threshold is done for
>>>>>> each loop packet, the total CPU utilization of python3 is about 0.75%
>>>>>> With mqtt and without calculation of sunshine threshold : 0.5% of
>>>>>> total CPU.
>>>>>>
>>>>>> So one can estimate that 0.25 % of total CPU is needed for the
>>>>>> calculation of the threshold value for each LOOP packet.
>>>>>>
>>>>>>
>>>>>> Le 9 juin 2022 à 22:26, 'Peter Fletcher' via weewx-user <
>>>>>> weewx...@googlegroups.com> a écrit :
>>>>>>
>>>>>> After some experimentation, I found that the radiation value in the
>>>>>> VP2 LOOP packets does, indeed, normally change every 50-52 seconds, but,
>>>>>> perhaps about a fifth of the 'gaps' are a *multiple* of that time -
>>>>>> most often 100+ or 150+ seconds, but occasionally more than that (I saw
>>>>>> one
>>>>>> 250+ second 'gap'). I saw this under conditions of variable sunshine and
>>>>>> clouds when it seemed unlikely that the actual radiation value would
>>>>>> have
>>>>>> been precisely constant for that length of time, so I am not sure
>>>>>> exactly
>>>>>> what is going on. In any event, I am revising the code I am using on the
>>>>>> basis of doing the threshold calculation when the radiation level
>>>>>> changes,
>>>>>> but at least every minute, if it remains constant for more than the
>>>>>> normal
>>>>>> 50-52 seconds..
>>>>>>
>>>>>> On Sunday, June 5, 2022 at 12:33:47 PM UTC-4 jterr...@gmail.com
>>>>>> wrote:
>>>>>>
>>>>>>> I think it is also OK to do an average for every 30 seconds. It
>>>>>>> depends also on the weather station used.
>>>>>>> For instance, a Davis Vantage Pro 2 ISS transmits an updated solar
>>>>>>> radiation value every 50 to 60 seconds. So with this weather station,
>>>>>>> even
>>>>>>> a 1 minute average would not be very different since anyway the solar
>>>>>>> radiation values of the LOOP packet are the same for at least 50
>>>>>>> seconds.!
>>>>>>>
>>>>>>> Le 5 juin 2022 à 18:02, 'Peter Fletcher' via weewx-user <
>>>>>>> weewx...@googlegroups.com> a écrit :
>>>>>>>
>>>>>>> I chose to average the LOOP radiation readings and only to do the
>>>>>>> threshold calculation and make the sun/no sun determination every 30
>>>>>>> seconds because I thought doing it on every LOOP might overload LOOP
>>>>>>> processing (I am running weewx on a Pi 3B, which is also doing a few
>>>>>>> other
>>>>>>> things which use the CPU). If this is an unnecessary concern, as it may
>>>>>>> very well be, your modified code is much cleaner than mine.
>>>>>>>
>>>>>>> On Saturday, June 4, 2022 at 12:41:08 PM UTC-4 jterr...@gmail.com
>>>>>>> wrote:
>>>>>>>
>>>>>>>> It is a very good idea to calculate the sunshine duration for each
>>>>>>>> LOOP packet and sum these values to make the final archive sunshine
>>>>>>>> duration. I have modified my script accordingly :
>>>>>>>> https://github.com/Jterrettaz/sunduration.
>>>>>>>> The logic is the following : for each received LOOP packet, the
>>>>>>>> radiation is compared to a calculated threshold. If the radiation is
>>>>>>>> above
>>>>>>>> the threshold value, the sunshine time for the LOOP packet is equal to
>>>>>>>> the
>>>>>>>> time elapsed between the previous loop packet and this packet (most
>>>>>>>> of the
>>>>>>>> time 2 seconds with a Vantage Davis Pro).
>>>>>>>> The final archive sunshine duration is the sum of all the LOOP
>>>>>>>> value within the archive period.
>>>>>>>> Le vendredi 3 juin 2022 à 21:59:36 UTC+2, Peter Fletcher a écrit :
>>>>>>>>
>>>>>>>>> That makes some sense when you are getting data from an 'external'
>>>>>>>>> sensor, though there are (IMHO) simpler ways of doing it. weewx
>>>>>>>>> already has
>>>>>>>>> access to the LOOP radiation data from the VP2, so handling the
>>>>>>>>> processing
>>>>>>>>> and data storage within weewx makes more sense to me in this case.
>>>>>>>>>
>>>>>>>>> On Friday, June 3, 2022 at 3:24:23 PM UTC-4 vince wrote:
>>>>>>>>>
>>>>>>>>>> On Friday, June 3, 2022 at 11:17:00 AM UTC-7 Meteo Oberwallis
>>>>>>>>>> wrote:
>>>>>>>>>>
>>>>>>>>>>> if the interval of Weewx and the data logger is set to 10
>>>>>>>>>>> minutes, I would have liked to read the value of the solar sensor
>>>>>>>>>>> every
>>>>>>>>>>> minute and then write it into a separate .sdb database as possible
>>>>>>>>>>> sunshine.
>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>> Personally I'd use an external program called via cron and
>>>>>>>>>> posting a message to a MQTT topic. Have weewx subscribe to that
>>>>>>>>>> topic to
>>>>>>>>>> get the data into your db.
>>>>>>>>>>
>>>>>>>>>> This is how I used to get my DS18b20 temperature sensor data into
>>>>>>>>>> weewx.
>>>>>>>>>>
>>>>>>>>>>
>>>>>>> --
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>>>>>>>
>>>>>>> <https://groups.google.com/d/msgid/weewx-user/0e631671-0a74-4963-9f1c-e5f81bc7c366n%40googlegroups.com?utm_medium=email&utm_source=footer>
>>>>>>> .
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>> --
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>>>>>>
>>>>>> <https://groups.google.com/d/msgid/weewx-user/f0ecc86f-a615-4a24-a43f-ee0d3963b8adn%40googlegroups.com?utm_medium=email&utm_source=footer>
>>>>>> .
>>>>>>
>>>>>>
>>>>>>
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